Negative Focal Length and Convex Mirrors: Is 1/di Negative?

[luysion]

Hey,
When dealing with convex mirrors I know that the image will always be virtual,upright and diminished. So when I am using descartes's formulae i know that for convex mirrors that the focal length is negative, but does my 1/di become negative? because virtual images have a negative height and distance.

Cheers

 

[Doc Al]

Yes, the image distance is negative for a convex mirror. (This follows directly from the spherical mirror equation.)